Continuously loaded conductor



July 19, 1932. w. c ELLIS 1,368,315

CONTINUOUSLY LOADED CONDUCTOR Filed June 9, 1951 INVENTOR W CELL/S ATTORNEY Patented July 19, 1932 UNITED STATES PATENT OFFICE WILLIAM C. ELLIS, F ROCKVILLE CENTER, NEW YORK, ASSIGN OR TO BELL TELEPHONE LABORATORIES, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK CONT'INUOUSLY LOADED CONDUCTOR Application filed June 9, 1931.

The present invention relates to the manufacture of continuously loaded electric cables. The object of the invent-ion is to provide an effective method of overcoming the wellknown diificulties arising during the annealing to which the loaded conductor is usually subject after loading, particularly when it is loaded with materials such as iron-nickel, and iron-nickel-cobalt alloys and their derivatives. The problem to be solved is essentially that of providing looseness of the magnetic loading material from the copper or like conductor upon which it is usually wound in tape or wire form. Such looseness allows for the relative expansibility of the copper as compared with that of the magnetic material, which would otherwise cause undesirable stresses in the magnetic material when the conductor is annealed and cooled, whereby the magnetic properties of the loading mate rial would be seriously impaired. p

Prior to the present invention, various proposals have been advanced to overcome the 'difiicultyQ The prior proposals have covered such expedients as the application of paper, varnish, or other combustible carbonaceous materials or thread strands or wires of fusible material over the core and under the magnetic material, the paper, threads, or Wire thus applied perishing either by combustion or fusion while the loaded core is being heated up to annealing temperature, thereby leaving the loading material so slack on the core that undesirable stresses between the two are impossible. It'has also been proposed to loosen the loading by means of a refractory powder which is initially caused-to adhere to the conductor by means of a volatile liquid binder which is driven off by heating to 400 C. before the core acquires its annealing temperature, and in accordance with still another proposal, gutta percha has been applied to the core under the loading material, whi h material melts during the annealing. It has also been proposed to use self-oxidizing materials or materials combined with oxidizing substances to be removed by chemical reaction under the influence of heat. It has also been proposed to employ as spacing ma- 'ing.

Serial No. 543,244.

terials soluble substances and dissolve them out by solvents prior to the heat treating process.

All the above suggestions have the draw- 7 possible, to avoid employing an energetic chemical reaction to remove the spacingmaterial since there is always danger ofdamaging the conductor or the loading. Application of solvents is inconvenient and expensive.

To avoid all of these several difficulties,

in accordance with the present invention a volatile material substantially solid at room temperature is applied over the conductor and under the magnetic loading material and,

if desired, between the layers of the magnetic loading material if tlierefl'are several, the

solid substance being such as will become vaporized before the annealing of the conductor or in the initial stages of the anneal- A suitable substance is parafiin wax of which most samples melt at 40 to C. and which volatilizes at about 300 C. This material may be readily applied to thevconductoras required and in controllable thickness by drawing the unloaded conductor through a bath of molten wax at the requisite speed. Thewax cools rapidly in air forming a substantial separator over which the magnetic material can be applied by any usual or suitable method.

Special means or methods may be employed to remove the vapors of the spacing material more rapidly and completely. When the loaded conductor is heated up during annealing, for example, in a continuous annealing tube, the wax will boil off ,at temperatures below @00 C. and the vapors may be swept out by the stream of nitrogen in which the conductor is annealed, for example, asset forth inthe specification of United States Letters Patent 1,586,897 granted June 1, 1926 to Harris, leaving the loading material desirably loose. Practically no residue will be left behind on the conductor after the wax has been driven OE, and all vapors and gases Will be swept out the cool end of the annealing tube thus reducing the probability of. injury to the. copper conductorathigher temperatures. 7

' Another substance useful as a spacing material is paradichlorbenzene. This substance meltsat 53 Sand evaporates at a relaever low temperature. In fact it evaporates in a considerable period of time at room temperature, and consequently when it is used and the loaded conductors are laid aside for several days or weeks, substantially all the spacing material. will have disappeared; from. the: conductor. @ther suitable substances are naphthalene, camphor, halowax; (a. mixture of. chlorinated. napthalenes melting at. about. 80 C. and boiling at about 28.0 C. to 364 C.) .henzoic ac'id',.1nelting at about 121;. C. and boiling at about 249? C., phthal'lic anhydride, diphenyh. and other waxesofl ow. boiling point. such as paradheres and. cools readily to form a smooth adherent coating on the conductor. -.Many

crystalline materials,. however, when their boiling. and melting points are suitable adhere well to. the copper conductor, and serve the purpose. A

Themolten material. may be applied" entirely around the surface of the conductor -or, to? onev side only; It may also be applied to. the: under. side. of the magnetic loading tape heforelaying the; tape on. the conductor. The conductor may be passed by suitable means through a hath ofthe moltenma- -teria l, ,thenceto the serving. machine forapplying the magnetic tape and then stored on.- a reel or led. immediately to the heat treating furnace.

The drawing illustrates a. loaded: conductor with pa'rt'sbrol'ren. away to. show the several layers. prior to subjecting the conductor to the heat treating process.

In thev drawing the central conductor cons sts of copper wire-1 surrounded by the usual fiat tapes 2. On the external surface of the tapes. 2 is covered or. otherwise simply applied a' layer 3- or material of the kind herei'nbeiz'ore. described, for example, napthalene,

.campho'r: or 'paradichlorbenzene, In the early stages ofthe heat treatment-the layer will evaporate: and leavev the. loading material l in a desirable loose and unstrained condition.

. What is claimed is: v

1. A process of manufacturing an article such. as a continuously load'ed submarine cable, comprising acentral. conductor and a wrapping or wrappings aboutthe conductor of material which it is required to maintain relatively loosely on the conductor during a heating process, characterized by the application to the conductor and under or between 4. A process according to claim 1 in. which the volatile mate-rial applied to'the conductor is a cyclic hydrocarbon (including derivatives) which is solidat room temperatureand evaporates below 400 C. at, atmospheric pressure..

5. A process according to claim 1 in. which the. volatile material-is a paraiiin hydrocarbon (including derivatives) which is solid at room temperature and evaporating around or below 6.. A process according to claiml in which the volatile material is paraflin:

7. A process according toclaim 1 in. which i the substanceapplied to the conductor-is paradichlorbenzene. I

8. A process according to claim 1 in which astream. of gas is utilized to-carry off the vapors of the volatile solid from the high: temperature zone of the heating towhich the con- :ductor is subjected. I I I 9.. A process according to claim 1 in which the evaporation. of solid material is largely accomplished in an atmosphere consisting principally of nitrogen.

10. A process in accordance with claim 1 in which the volatile material is. selected from the grou-pfof organic substances which aresolidbut tend to evaporate slowly at high room 1 temperatures.

In. witness whereof, I hereunto subscribe my name this 3d day of June, 1931.

. WILLIAM C. ELLIS. 

